November 2015

Forty-eight years ago this month, the No. 3 USAF/North American X-15 research aircraft broke-up during a steep dive from an apogee of 266,000 feet. The pilot, USAF Major Michael J. Adams, perished when his aircraft was ripped apart by aerodynamic forces as it passed through 65,000 feet at more than 2,500 mph.

The hypersonic X-15 was arguably the most productive X-Plane of all time. Between 1959 and 1968, a trio of X-15 aircraft were flown by a dozen pilots for a total of 199 official flight research missions. Along the way, the fabled X-15 established manned aircraft records for speed (4,534 mph; Mach 6.72) and altitude (354,200 feet).

The X-15 was a rocket, aircraft and spacecraft all rolled into one. Burning anhydrous ammonia and liquid oxygen, its XLR-99 rocket engine generated 57,000 lbs of sea level thrust. Reaction controls were required for flight in vacuum. Each flight also required careful management of aircraft energy state to ensure a successful, one attempt only, unpowered landing.

On Wednesday, 15 November 1967, the No. 3 X-15 (S/N 56-6672) made the 191st flight of the X-15 Program. In the cockpit was USAF Major Michael J. Adams making his 7th flight in the X-15. He had been flying the aircraft since October of 1966. Like all X-15 pilots, he was a skilled, accomplished test pilot used to dealing with the demands and high risk of flight research work.

X-15 Ship No. 3 was launched from its B-52B (S/N 52-0008) mothership over Nevada’s Delamar Dry Lake at 18:30 UTC. As the X-15 fell away from the launch aircraft at Mach 0.82 and 45,000 feet, Adams fired the XLR-99 and started uphill along a trajectory that was supposed to top-out around 250,000 feet. If all went well, Adams would land on Rogers Dry Lake at Edwards Air Force Base in California roughly 10 minutes later.

Around 85,000 on the way upstairs, Adams became distracted when an electrical disturbance from an onboard flight experiment adversely affected the X-15’s flight control system, flight computer and inertial reference system. As a result, data on several key cockpit displays became corrupted. Though with some difficulty, Adams pressed-on with the flight which peaked-out around 266,000 feet approximately three (3) minutes from launch.

As a result of degraded flight systems and perhaps disoriented by vertigo, Mike Adams soon discovered that his aircraft was veering from the intended heading. He indicated to the control room at Edwards that his steed was not controlling correctly. Passing through 230,000 feet, Adams cryptically radioed that he was in a Mach 5 spin. Mission control was stunned. There was nothing in the X-15 flight manual that even addressed such a possibility.

Incredibly, Mike Adams somehow managed to recover from his hypersonic spin as the X-15 passed through 118,000 feet. However, the aircraft was inverted and in a 45-degree dive at Mach 4.7. Still, Adams may very well have recovered from this precarious flight state but for the appearance of another flight system problem just as he recovered the X-15 from its horrific spin.

X-15 Ship No. 3 was configured with a Minneapolis-Honeywell adaptive flight control system (AFCS). Known as the MH-96, the AFCS was supposed to help the pilot control the X-15 during high performance flight. Unfortunately, the unit entered a limit-cycle oscillation just after spin recovery and failed to change gains as the dynamic pressure rapidly increased during Ship No. 3’s final descent. This anomaly saturated the X-15 flight control system and effectively overrode manual inputs from the pilot.

The limit-cycle oscillation drove the X-15’s pitch rate to intolerably-high values in the face of rapidly increasing dynamic pressure. Passing through 65,000 feet at better than 2,500 mph (Mach 3.9), Ship No. 3 came apart northeast of Johannesburg, California. The main wreckage impacted just northwest of Cuddeback Dry Lake. Mike Adams had made his final flight.

For his flight to 266,000 feet, USAF Major Michael J. Adams was posthumously awarded Astronaut Wings by the United States Air Force. His name was included on the roll of the Astronaut Memorial at Kennedy Space Center (KSC) in 1991. Finally, on Saturday, 08 May 2004, a small memorial was erected to the memory of Major Adams near his X-15 crash site situated roughly 39 miles northeast of Edwards Air Force Base.

Eleven years ago today, the NASA X-43A scramjet-powered flight research vehicle reached a record speed of over 6,600 mph (Mach 9.68). In doing so, the X-43A eclipsed its own record speed of Mach 6.83 (4,600 mph) and became the fastest airbreathing aircraft of all time.

In 1996, NASA initiated a technology demonstration program known as HYPER-X. The central goal of the HYPER-X Program was to successfully demonstrate sustained supersonic combustion and thrust production of a flight-scale scramjet propulsion system at speeds up to Mach 10.

Also known as the HYPER-X Research Vehicle (HXRV), the X-43A aircraft was a scramjet test bed. The aircraft measured 12 feet in length, 5 feet in width, and weighed close to 3,000 pounds. The X-43A was boosted to scramjet take-over speeds with a modified Orbital Sciences Pegasus rocket booster.

The combined HXRV-Pegasus stack was referred to as the HYPER-X Launch Vehicle (HXLV). Measuring approximately 50 feet in length, the HXLV weighed slightly more than 41,000 pounds. The HXLV was air-launched from a B-52 mothership. Together, the entire assemblage constituted a 3-stage vehicle.

The third and final flight of the HYPER-X program took place on Tuesday, 16 November 2004. The flight originated from Edwards Air Force Base, California. Using Runway 04, NASA’s venerable B-52B (S/N 52-0008) started its take-off roll at approximately 21:08 UTC. The aircraft then headed for the Pacific Ocean launch point located just west of San Nicholas Island.

At 22:34:43 UTC, the HXLV fell away from the B-52B mothership. Following a 5 second free fall, rocket motor ignition occurred and the HXLV initiated a pull-up to start its climb and acceleration to the test window. It took the HXLV 75 seconds to reach a speed of slightly over Mach 10.

Following rocket motor burnout and a brief coast period, the HXRV (X-43A) successfully separated from the Pegasus booster at 109,440 feet and Mach 9.74. The HXRV scramjet was operative by Mach 9.68. Supersonic combustion and thrust production were successfully achieved. Total engine-on duration was approximately 11 seconds.

As the X-43A decelerated along its post-burn descent flight path, the aircraft performed a series of data gathering flight maneuvers. A vast quantity of high-quality aerodynamic and flight control system data were acquired for Mach numbers ranging from hypersonic to transonic. Finally, the X-43A impacted the Pacific Ocean at a point about 850 nautical miles due west of its launch location. Total flight time was approximately 15 minutes.

The HYPER-X Program was now history. Supersonic combustion and thrust production of an airframe-integrated scramjet had indeed been achieved for the first time in flight; a goal that dated back to before the X-15 Program. Along the way, the X-43A established a speed record for airbreathing aircraft and earned several Guinness World Records for its efforts.

As a footnote to the X-43A story, the HYPER-X Flight 3 mission would also be the last for NASA’s fabled B-52B mothership. The aircraft that launched many of the historic X-15, M2-F2, M2-F3, X- 24A, X-24B and HL-10 flight research missions, and all three HYPER-X flights, would take to the air no more. In tribute, B-52B (S/N 52-0008) now occupies a place of honor at a point near the North Gate of Edwards Air Force Base.

Fifty-four years ago this week, the USAF/NASA/North American X-15 became the first manned aircraft to exceed Mach 6. United States Air Force test pilot Major Robert M. White was at the controls of the legendary hypersonic flight research aircraft.

The North American X-15 was the first manned hypersonic aircraft. It was designed, engineered, constructed and first flown in the 1950’s. As originally conceived, the X-15 was designed to reach 4,000 mph (Mach 6) and 250,000 feet. Before its flight test career was over, the type would meet and exceed both performance goals.

North American built a trio of X-15 airframes; Ship No. 1 (S/N 56-6670), Ship No. 2 (56-6671) and Ship No. 3 (56-6672). The X-15 measured 50 feet in length, had a wing span of 22 feet and a GTOW of 33,000 lbs. Ship No. 2 would later be modified to the X-15A-2 enhanced performance configuration. The X-15A-2 had a length of 52.5 feet and a GTOW of around 56,000 lbs.

The Reaction Motors XLR-99 rocket engine powered the X-15. The small, but mighty XLR-99 generated 57,000 pounds of sea level thrust at full-throttle. It weighed only 910 pounds. The XLR-99 used anhydrous ammonia and LOX as propellants. Burn time varied between 83 seconds for the stock X-15 and about 150 seconds for the X-15A-2.

The X-15 was carried to drop conditions (typically Mach 0.8 at 42,000 feet) by a B-52 mothership. A pair of aircraft were used for this purpose; a B-52A (S/N 52-003) and a B-52B (S/N 52-008). Once dropped from the mothership, the X-15 pilot lit the XLR-99 to accelerate the aircraft. The X-15A-2 also carried a pair of drop tanks which provided propellants for a longer burn time than was possible with the stock X-15 flight.

The X-15 employed both aerodynamic and reaction flight controls. The latter were required to maintain vehicle attitude in space-equivalent flight. The X-15 pilot wore a full-pressure suit in consequence of the aircraft’s extreme altitude capability. The typical X-15 drop-to-landing flight duration was on the order of 10 minutes. All X-15 landings were performed deadstick.

On Thursday, 09 November 1961, USAF Major Robert M. White would fly his 11th X-15 mission. The X-15 and White had already become respectively the first aircraft and pilot to hit Mach 4 and Mach 5. On this particular day, White would be at the controls of X-15 Ship No. 2. The planned maximum Mach number for the mission was Mach 6.

At 17:57:17 UTC of the aforementioned day, X-15 Ship No. 2 was launched from the B-52B mothership commanded by USAF Captain Jack Allavie. Bob White lit the XLR-99 and pulled into a steep climb. Mid-way through the climb, White pushed-over and ultimately leveled-off at 101,600 feet. XLR-99 burnout occurred 83 seconds after ignition. At this point, White was traveling at 4,093 mph or Mach 6.04.

On this record flight, the X-15 was exposed to the most severe aerodynamic heating environment it had experienced to date. Decelerating through Mach 2.7, the right window pane on the X-15’s canopy shattered due to thermal stress. The glass pane remained intact, but White could not see out of it. Fortunately, he could see out of the left pane and made a successful deadstick landing on Rogers Dry Lake at Edwards AFB.

For his Mach 6+ flight, Bob White was a recipient of both the 1961 Collier Trophy and the Iven C. Kincheloe Award. The year before, White had received the Harmon Trophy for his X-15 flight test work. He would go on to fly the X-15 to a still-standing FAI altitude record of 314,750 feet in July of 1962. For this accomplishment, White was awarded USAF Astronaut Wings.

Bob White flew the X-15 a total of sixteen (16) times. He was one (1) of only twelve (12) men to fly the aircraft. White left X-15 Program and Edwards AFB in 1963. He went on to serve his country in numerous capacities as a member of the Air Force including flying 70 combat missions in Viet Nam. He returned to Edwards AFB as AFFTC Commander in August of 1970.

Major General Robert M. White retired from the United States Air Force in 1981. During his period of military service, he received numerous decorations and awards including the Air Force Cross, Distinguished Service Medal, Silver Star with three oak leaf clusters, Legion of Merit, Distinguished Flying Cross with four oak leaf clusters, Bronze Star Medal, and Air Medal with 16 oak leaf clusters.

Bob White was a true American hero. He was one of those heroes who neither sought nor received much notoreity for his accomplishments. He served his country and the aviation profession well. Bob White’s final flight occurred on Wednesday, 17 March 2010. He was 85 years of age.

Thirty-four years ago this month, the Space Shuttle Columbia completed the second mission of the Space Shuttle Program. Designated STS-2, the mission marked the first reuse of a space vehicle for manned orbital flight.

America’s early manned spacecraft – Mercury, Gemini and Apollo – were single-flight vehicles. That is, a new spacecraft was required for each space mission. This was appropriate for meeting the aims of the early space program which concentrated on getting America to the moon before the end of the 1960’s.

The concept of space vehicle reusability came into vogue with the introduction of the Space Transportation System (STS). The original goal of the STS was to provide frequent and routine access to space via a fleet of Space Shuttle vehicles. For the STS to achieve economic viability, this meant flying a Space Shuttle once every two weeks. History records that this projected flight rate was much too optimistic.

The Space Shuttle vehicle was ultimately configured as a 3-element system consisting of (1) a winged orbiter, (2) a pair of solid rocket boosters (SRB’s) and (3) an external tank (ET). Both the orbiter and the SRB’s were designed to be reusable. The ET would be the only disposable element of the system since higher costs would be incurred in the recovery and refurbishment of this piece of flight hardware than in simply using a new one for each flight.

The Space Shuttle was designed to haul large payloads; on the order of 60,000 and 50,00 lbs into and out of orbit, respectively. With a maximum landing weight of 230,000 lbs, the Space Shuttle Orbiter needed wings to generate the required aerodynamic lift force. Wings were needed to satisfy the Orbiter’s 1,100-nm entry cross range requirement as well.

Following the successful first flight (STS-1) of the Space Shuttle Columbia in April of 1981, preparations began immediately to ready the Orbiter for its equally monumental second flight. The STS-2 flight crew would consist of Commander Joe Henry Engle and Pilot Richard Harrison Truly. STS-2 would be the first orbital spaceflight for both men.

On Thursday, 12 November 1981, the Space Shuttle Columbia lifted-off at 15:09:59 UTC from Cape Canaveral’s LC-39A. Ascent flight was nominal and Columbia was placed into a 125-nm x 120-nm orbit. At this point, Columbia became the first manned spacecraft to achieve Earth-orbit twice. It was an extra special occasion for Richard Truly inasmuch as it was his 44th birthday.

Engle and Truly anticipated 5-days in orbit with their orbital steed. However, one of Columbia’s three fuel cells failed early-on and the mission was reduced to just over two days. Nonetheless, the crew achieved 90 percent of the mission’s goals. They even remained awake during a scheduled sleep period to exercise the new Canadian Remote Manipulator System (RMS).

On Saturday, 14 November 1981, Columbia and her crew successfully completed STS-2 by landing on Rogers Dry Lake at Edwards Air Force Base, California. Main gear touchdown occurred at 21:23:11 UTC. Joe Engle flew the entire reentry manually. He holds the distinction of being the only pilot to manually fly a lifting space vehicle all the way from orbit to landing. Engle completed a total of 29 Programmed Test Input (PTI) aerodynamic maneuvers in the process.

STS-2 was a monumental success. Columbia became the first space vehicle to be reused for manned orbital space operations. Other Orbiters would follow including Challenger, Atlantis, Discovery and Endeavor. The final mission of the Space Shuttle Program (STS-135) was flown by Atlantis in July 2011.

As a footnote, Joe Engle went on to command one more Space Shuttle mission in 1985 (STS-51I). He retired from the USAF in November of 1986. Richard Truly served as Commander of STS-8 in 1983. That mission featured the first night launch and landing of the Space Shuttle. Richard Truly also served as NASA Administrator from May of 1989 to May of 1992.